Non-volatile memory systems, such as flash memory devices, have been widely adopted for use in consumer products. Flash memory devices may be found in different forms, for example in the form of a portable memory card that can be carried between host devices or as a solid state disk (SSD) embedded in a host device. When writing data to a conventional flash memory device, a host typically writes data to, and reads data from, addresses within a logical address space of the memory system. For example, the memory in the flash memory device may be divided into blocks, in which data from the host is written. To write data into a block of the flash memory device, the block is erased and then programmed by writing data into the cells of the block. Each time a block undergoes a program/erase (P/E) cycle, a counter may be incremented. The total number of PIE cycles for a respective block may be designated as the erased count or the “hot count” for the respective block.
Through use, the blocks in the flash memory device may eventually fail. Therefore, flash memory devices typically attempt to level the wear across the blocks. In particular, wear levelling attempts to selects blocks so that erasures and re-writes are distributed evenly across the blocks. In this way, no single erase block prematurely fails due to a high concentration of write cycles. To accomplish the wear leveling, the flash memory device relies on the erased count of the blocks, selecting blocks with lower erased counts in the expectation of more evenly distributing the wear across the memory in the flash memory device.